He's remains quiet for a long time, studying her expression. Studying her presence in the Force, even, as much as he can without...touching the edges of her mind.

Then he nods, slowly. "Ok. Just calling him Vader from the moment he swore to serve Palpatine would probably be easiest but...I don't want to do that. I've seen the damage it did, that both Anakin and Ben, by the time Luke grew up, convinced themselves Vader destroyed Anakin, in some sort of spiritual sense. So I'm going to keep calling him Anakin, even though he hasn't done any of these things yet."